A variety of approaches and systems have been developed to monitor physical stress on a subject. Such monitoring approaches and systems may require manual observations and recordings, cumbersome wearable instruments, complex linkage algorithms, and/or complex three-dimensional (3D) tracking. More specifically, the developed monitoring approaches and systems may require detailed manual measurements, manual observations over a long period of time, observer training, sensors on a subject, and/or complex recording devices. Of the known approaches and systems for monitoring physical stress on a subject, each has certain advantages and disadvantages.